Apparent ileal digestibility (AID) of crude protein (CP) and amino acids (AA) is affected by CP and AA concentrations in diets because of the different contributions of endogenous N and AA to the ileal digesta from pigs fed diets with different concentrations of CP. Because of the influence of dietary CP and AA on calculated values for AID, values for AID obtained in individual feed ingredients are not always additive in mixed diets if the concentration of CP and AA in the mixed diet is different from that of the ingredients. Therefore, values for standardized ileal digestibility (SID) of CP and AA, which are corrected for the basal ileal endogenous losses of CP and AA, are used in diet formulations to avoid the influence of endogenous AA on digestibility values, and SID values are, therefore, additive in mixed diets.

Sunflower meal (SFM) is a protein source that can be included in diets for pigs and other livestock species. In addition to providing amino acids, SFM also provide energy and other nutrients to diets, but because of the high concentration of fiber, SFM does not contain as much energy as other oilseed meals. The nutritive value of SFM depend on growing area, degree of de-hulling, and oil extraction process. Sunflower meal is obtained through a prepress-solvent extraction method, which yields a meal product with less than 3% fat. However, a double press procedure without solvent extraction may also be used to remove oil from the seeds, which results in generation of a co-product called sunflower expellers (SFE). Because the double-press procedure is less efficient in removing oil from the seeds, SFE contains between 6 and 10% oil. The concentration of fiber and protein also varies among different sources of SFM and SFE and is largely determined by the degree of de-hulling that takes place prior to oil extraction. Because the hulls are very high in fiber, there is a linear relationship between fiber concentration and the concentration of hulls in SFM and SFE, and there is a negative relationship between fiber and protein concentrations. However, data on the digestibility of nutrients and energy and concentrations of digestible energy (DE) and metabolizable energy (ME) in different sources of sunflower co-products are limited. Therefore, the objective of this research was to test the null hypothesis that there are no differences in the apparent total tract digestibility (ATTD) of dry matter, crude protein, fat, and gross energy and concentrations of DE and ME in SFM fed to growing pigs. The second objective was to test the null hypothesis that there are no difference in the ATTD of nutrients and energy concentrations between SFM and SFE fed to growing pigs.

Lee, S. A., M. R. Bedford, H. H. Stein. 2021. Comparative digestibility and retention of calcium and phosphorus in normal- and high-phytate diets fed to gestating sows and growing pigs. Animal Feed Science and Technology 280 (2021) 115084. doi.org/10.1016/j.anifeedsci.2021.115084. Link to full text.

Lee, Su A, Laia Blavi, Diego M. D. L. Navarro, and Hans H. Stein. 2021. Addition of hydrochloric acid to collection bags or collection containers did not change basal endogenous losses or ileal digestibility of amino acid in corn, soybean meal, or wheat middlings fed to growing pigs. Animal Bioscience Vol. 34, No. 10:1632-1642 October 2021. doi.org/10.5713/ab.20.0838.

Ibagon, Jimena A., Su A Lee, and Hans H. Stein. 2021. Sunflower expellers have greater ileal digestibility of amino acids than sunflower meal, but there are only minor variations among different sources of sunflower meal when fed to growing pigs. Journal of Animal Science, 2021, Vol. 99, No.

Lagos, L. Vanessa, Su A Lee, Mike R. Bedford, and Hans H. Stein. 2021. Reduced concentrations of limestone and monocalcium phosphate in diets without or with microbial phytase did not influence gastric pH, fecal score, or growth performance, but reduced bone ash and serum albumin in weanling pigs. Transl. Anim. Sci. 2021.5:1-10. doi.org/10.1093/tas/txab115.

Phytic acid is the main storage of P in plants, and most P in plant feed ingredients is bound in the phytate complex. Because pigs do not secrete phytase, an enzyme to hydrolyze inositol bonds in phytate, the utilization of P by pigs is very low. Addition of supplemental phytase to diets thus results in release of P and increases P utilization by pigs. However, all enzymes have a special recognition mechanism called specificity that works only with molecules that fit to active sites of the enzyme. Therefore, it is important to know how much of P is phytate-bound and how much of the P in a given diet is not phytate-bound.